Decks, Patios, Porches and Docks - OK to cover existing deck with composite decking material?

We have an older deck and not sure whether it's a good idea to lay composite decking material over the existing wood?
Thanks

Not something I would do if you mean straight over the existing deck. It would trap moisture and when the wood underneath starts to rot..then what?

Now, if you pull the existing decking up and the framing members are still solid..then no reason why you couldn't put down synthetic. Thats the way better decks are built. They don't have any synthetic structural material...yet.

Thanks for your response...I appreciate it!

If your joists are spaced correctly for the material thickness/rating. Check this point --- it is very important!
Be safe, Gary

Thanks for your response...we'll check the spacing on the joists. Would the spacing be the same for composite vs. wood pieces of the same size if the composite material is not as heavy as wood?

The spacing will normally be closer for composits of the same size as wood.

You would need to decide on the material you want first. No Pro, but most require 16" on center and some people recommend going 12" on center to eliminate any "bounce". Thats why you would need to know what exists now..so you can be aware of how much addl work will be required.

I've seen decks with 2X6 used as the floor and the joists were spaced 24", w/ only a bit of flex. That would never work for regular 5/4 decking.

Hope I was clear on this..lol

Spacing of joists is critical because composite is not as stiff as real wood. Follow composite manufacturer's specs for joist spacing.

Thanks again everyone. All the info is great...so glad I found this site!